Quick answer
If the sinks get hot but the shower stays lukewarm, the problem is in the shower valve: most single-handle valves have an anti-scald limit stop that caps how far the handle turns toward hot, and it can be set too low, or the mixing cartridge is worn or clogged. Remove the handle, adjust the limit stop a little toward hot, and test. If every tap is short of hot water, the water heater is the cause. The CPSC recommends a water heater setting of 120°F to prevent scalds. Call (888) 217-6781 to reach a plumbing company taking calls in your ZIP.
Follow the short menu, then your 5-digit ZIP. The line goes quiet for a few seconds while it connects; stay on. If it does not connect, call once more: companies taking calls change minute to minute.
Written & reviewed by Marcus ReedIICRC WRT
Reviewed November 4, 2026· Next review May 2027
If the kitchen and bathroom sinks get hot but the shower stays lukewarm, the water heater is fine. The cause is in the shower valve, and on most single-handle showers it is a small part you may be able to adjust.
First, Test a Sink
- Sinks hot, shower lukewarm: the shower valve.
- Every tap lukewarm or cold: the water heater. See no hot water in the house or, for electric tanks, the reset button.
The Limit Stop
Most single-handle shower valves made in recent decades have an anti-scald limit stop, a plastic stop or toothed ring under the handle that limits how far it turns toward hot. Installers set it to protect against scalding; it is sometimes set too cautiously, or knocked out of place when the trim is replaced.
- 1Remove the handle; a screw sits under a cap or in the side.
- 2Find the stop on the valve stem. Pull it out, rotate it a notch or two toward hot, and push it back.
- 3Replace the handle and test with your hand before stepping in.
Adjust in small steps. The CPSC recommends setting water heaters to 120°F and notes that hotter tap water can scald quickly, especially children and older adults.
Talk to a plumber about this
One call reaches a plumbing company taking calls in your ZIP.
The Cartridge
A worn or grit-clogged mixing cartridge can block the hot side. Signs: hot that fades during the shower, or a handle that turns to full hot with little change. Shut off the water, remove the cartridge, rinse it, or replace it with an exact match. See shower head dripping for removal steps.
Pressure-Balance Valves
Many showers use a pressure-balance valve that cuts hot flow when cold pressure drops, such as when a toilet flushes. If the spool inside sticks, the shower runs cooler than it should. Cleaning or replacing the cartridge fixes it.
The Call
Call when the cartridge is seized, the valve has no stops and you cannot shut off the water, or adjustments do not help. (888) 217-6781 connects you to a plumbing company taking calls in your ZIP. Follow the short menu, enter your 5-digit ZIP and stay on while it connects; if it does not connect, call once more, because the companies taking calls change minute to minute.
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Frequently Asked Questions
Why is my shower not hot but my sink is?
The shower valve's anti-scald limit stop is set too low, or its mixing cartridge is worn or blocked on the hot side.
How do I adjust the hot water limit on my shower?
On many single-handle valves, remove the handle to reach a plastic stop or gear on the valve stem. Rotating it lets the handle turn further toward hot. Adjust in small steps and test, to avoid scalding.
Why did my shower get cold suddenly?
If every tap is cold, the water heater has a problem. If only the shower, a cartridge may have failed, or grit from plumbing work lodged in it.
Sources
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Disclaimer: HearthDry is an independent educational resource. This article is for informational purposes only and does not constitute professional, legal, or insurance advice. Consult licensed professionals before making decisions about your property or insurance claims.
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